Hepatitis C virus core antigen (HCVcAg) assays with signal amplification have high sensitivity and specificity and could potentially replace nucleic acid testing (NAT), according to a study in the Annals of Internal Medicine.

J. Morgan Freiman, MD, from the Boston Medical Center, Boston University School of Public Health, and colleagues sought to evaluate the diagnostic accuracy of active HCV infection among adults and children for 5 HCVcAg tests, compared with NAT. A diagnosis of HCV infection currently requires a positive HCV antibody screen and confirmatory NAT.


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The researchers conducted a web search of case–control, cross-sectional, cohort, or randomized trials that compared any of 5 HCVcAg tests with a NAT reference standard between 1990 and March 2016. Two independent reviewers extracted data and assessed quality with use of an adapted Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool.

The investigators found 44 studies that evaluated 5 index tests. Trials of the Abbott ARCHITECT HCV Ag assay had the highest quality, and those for the Ortho HCV Ag enzyme-linked immunosorbent assay (ELISA) had the lowest quality, according to Dr Freiman’s group.

A bivariate analysis found that the sensitivity and specificity, respectively, of the assays were: Abbott ARCHITECT, 93.4% and 98.8%; Ortho ELISA, 93.2% and 99.2%; and Hunan Jynda Bioengineering Group HCV Ag ELISA, 59.5% and 82.9%.

Insufficient data were available for a meta-analysis regarding the Fujirebio Lumipulse Ortho HCV Ag and Eiken Lumispot HCV Ag assays. In 3 quantitative studies that used the Abbott ARCHITECT, HCVcAg correlated closely with HCV RNA levels greater than 3,000 IU/mL.

“The HCVcAg assays with signal amplification have high sensitivity, high specificity, and good correlation with HCV RNA levels greater than 3000 IU/mL and have the potential to replace NAT in settings with high HCV prevalence,” concluded Dr Freiman and colleagues.


  1. Freiman JM, Tran TM, Schumacher SG, et al. Hepatitis C core antigen testing for diagnosis of hepatitis C virus infection: a systematic review and meta-analysis. Ann Intern Med. 2016 Sep 6;165(5):345-55. doi: 10.7326/M16-0065.